Lightning arrester



VJuly- 14, 1925.

E. A. EVERETT ET AL LIGHTNING ARRES TER Filed July 16 1921 2Y Sheets-Shea; 1

E. A. EVERETT ET AL LIGHTNING ARRESTER July 14, 1925.

Filed July 16 1921 2 Sheets-Sheet 2 /fn/f 0 5.; @E ,Wsw W Patented' July 14, 1925.

UNITED STATES PATENT- EDWABD-A. EVERETT, LONG-r ISLAND CITY, NEW YORK; AND lLILTON E.

EASTORANGE, NEW JERSEY; SAID oFFAICE.

y SMITH, or SMITH AssIGNoR To SAID EV'ERETT.

LIGHTNING Annnsm 'Application led July 16,

' To all 'wlw/m. z'zmay concern:

, Be it known that we, EDWARI') A. EvERETT, a resident of Long Island Cit in the county of Queens and State of New York, and

This invention relates to lightning `arresters and particularly toa type of lightning arrester for use `on electric circuits, lto protect the apparatus connected to these circuits and to discharge static electricity that may' accumulate on these circuits from lightning or other causes, and it has for an object to provide an arrester of this type i which is compact'and rugged and which may be disassembled and reassembledwithout the possibility of impairing itseiiciency.

' Another object is to provide a block of carwhich will borundum or other refractory material hav-y ing a high dielectric strength and able to stand lightning discharges with a large number of spark gap points arranged on its surface; also it has for an object to provide a receptacle for a refractory block hold this block in place after it rmay have been accidentally broken. Another vobject is to provide a comparatively large metallic contact surface fc. the refractory material which is tightly lsecured to the metallic clips supporting the arrester and a further object is to provide an ar-` rester of a comparatively small size which may be applied directly to electric instruments and terminals )as now found in commercialA use. These and .other objects of this invention will be more fullyunderstood from the following specification and the f accompanying drawings in whichv Fig. 1

shows a li htning arrester, artly in section, embo ying ourV invention, Fig. 2 is a detailed part for use with Fig. l, Figs. 3 and 4 are sectional elevations showing modifications in the method of securing the various 'parts of the arrester togetheryFig. 5 shows one application of this invention to the terminal blocks used in lcertain electric circuits, Fig. 6 is an elevation corresponding to Fig. -5, Fig. 7 shows the application of our invention to a type of lightning arrester provided with a choke coil, Fie. 8

1921. Serial No. 485,223. V

shows an application that may be used where thegwire terminals are close togther and Fig. 9 shows ow the spark gap may be adjusted.

This invention consists in providing a pair of strips for connecting to the terminals of an electric circuit and interposed between the ends of these strips is a block of carborundum or refractory material, preferably in the form of a circularfwheel and around this block are arranged a number of-saw teeth, producing a spark gap across the carborundum. Our invention resides in the detailed application of this idea and in the simplicity of construction, increased efiiciency and the comparatively small and inexpensive arrangement adopted.

Referring to Fig. l, l1 represents one terminal'strip and 12 is the opposite terminal strip.v The strip l1 may be provided with a slot 13 and the strip `12 may be provided with a similar slot whereby these strips may be inserted under the binding posts of a terminal to which the`wires of the circuit tobe protected are connected. The ends of the strips 11 and 12. are bent at right angles,

these turned up ends being arranged opposite each other and enclosing between them a pair of saw toothed, cup-shaped discs into which the carborundum wheel 19 fits snugly, the discs being arranged withthe saw teeth opposite. The disc for this purpose may be constructed as shown at 26, Fig. 2, having a hole, 27 yfor the bushing 20 and from this blank the teeth are turned into a cup-shaped disc as indicated in Fig. 1, the teeth being arranged opposite each other as shown at 28. The construction shown contemplates a separate part 'for the discs 26. However, it should be understood that cup-shaped ends witlr saw teeth may be formed in the ends of the terminal strips 11 and 12 vfor the same purpose as the discs 26, when assembled, become electrically an integral part of the strips ll and 12. When the carborundum wheel is enclosed in the discs 26, the ends of strips' 11 and 12 are rounded as indicated in F ig. 1 and clamped against the discs 26 by the bolt 32; Attention is here called to the large Contact area provided between the carborundumwheel and the discs and between the discs and the terminal strips and these surfaces are rmly and tightly held together by the bolt 32, nut 22v and m- I sulating collars for this wheel which strengthens it 'and' holdsy it in position if it. should become broken, thereby guarding Vagainst the possibility of terminal strips 11 and'12 becoming short circuited or displaced under. thesecon ditions. rv 4 In Fig. llthe terminal strip 11 is shown lplaced at right angles to the terminal strip 12. This is an attractive feature of the present construction as it enables the terminal strips to be placed lat any angle with relation to each other as may be found con# venient inmaking connections to the wire terminals. Y

Fig. l'also shows a ring vof ,glass or other suitable insulating material 30, held in posi tion by strips 11 and 12, arrangedto enclose the entire carborundum wheel an'd the spark gap points. This construction may be found desirable whereA anaccumulation of dust is likely to deposit between thespark .gap points. However, it is, to be noted that with the circular construction shown, the tendency for dust to accumulate between the sparkgap points is' greatly lessened Figl 3 shows va modified arrangement for.

holdin the parts together and includes a bolt w ,ich makes metallic contact with the carborundum'wheel. In this construction it willbe noted that the tubular bushing 2O is omitted and the collars 31 are provided with a shoulder which fits into an enlarged opening inlthelterminal .strips 11 and 12 and the discs 26. The hole in the Ycarborundum Wheel is the same size as the bolt 32 and therefore makes contact with the bolt. The outer portion/of the bolt may be provided 'with two nuts, 22 and ,22 as shown. These nuts engage a washer or a contact plate 32a which maybe used to electrically connect the carborundum wheels of adjacentl arresters together `by a link similar to the arran ement indicated at 56-7 Fig. 5.

e constructionshownin Fig. 4 provides.`

a'bolt of insulating material 35, which may be made of bakelite or other suitable mate-` rial and which has the end nuts 36 and washers 37 holding' the several parts to-\ Cil . This non-metallic bolt has certain advanv .Egther as shown. Thisl arrangement it will noted, leaves only one possible metallic path connecting the strips 11 'and 12, which 1s through the spark gaps of thediscs 26.

tages'when used on'high tension circuits..

In practlce carborundum has the property ofxdamping out an electric arc that rmight ldevelop between the spark gap i points;-

. whereas some other substances like carbon have a tendency to maintain the arc.

l If the arc 1s maintained a metallic path is eventu- Signal Associationand generally known as .an R. S. A. terminal. The terminals are supported 0n porcelain blocksA 51 and 52. lThe line wires are led to. terminal 53 and terminal 54. The arrangement l in Fig. 5

shows the application fortwo line circuits.

The arrester element is embodied in the terminal strip 11, maintaining the circuit be.

tween theterminals 5 3 4and 54 and in orderl that the discharge through the arrester mayv be grounded -a connecting strip 56 is provided 'between the binding screws 55 as shown, thisstripbeing continued between Aso last terminal connected-.to aground wire.

In this arrangement the carborundum v wheel'is placed horiz the connectingstrip 11a f om which it is insulated by the collar 31,v4 similar to Fig. 3.

The insulating collar 31 is omitted above the' top disc 26 with the result that strip` 56 connectsdirectly. to this disc as well as connecting with the carborundum wheel through bolt '55. This makes a grounded arrester tap to the conductors 11a. Boltl 55 is pro? vided with a square head 7 2 which fits a rellly'on the top of l i cess 73 in the topof the porcelain block 52, t l

Fig. 6. This prevents the bolt from turning when the nuts are adjusted. From Fig.

5 it will be noted that-the slotted openings.

in strips 11a enable these strips to be re moved from'the binding posts without removing the nuts. The strip 11EL in Figs. l5

. and' may of course be supported by only l lone terminal post, also the arrester. may be applied to the projecting vends of strips `'11g' where there is not suiiicient space between the terminals for this purpose.

.The arrangement shown in Fig. 7 includes a'type of lighting arresterprovided with a choke coil and tog which the construction of the present invention is adapted. This consists of an enlarged base .52%l` having a recess in the bottom to houselthe choke coil 71 which provides continuity for the circuit between terminals 53 and 54.I The construc tion of the arrester is similar to Fig. 3 in mwhich the bolt 55 makes contact with theV wheel 19and is linsulated -from the metallic p-arts by the collars 31-'31. Connecting strip 56 thus provides an independent connection to the carborundum wheel'which is ultimately grounded as in Fig. 5.

- In Fig. '8 our invention is shown applied l to a terminal block 52b where the wire termlnals 53 and 54 are `comparatively close together.

for thisadaption is similar Fig. 7 ,the ter- The construction .of the arrester.

85 each of theseterminals for a group and the f minal strips 1l and 12 being angularly positioned in a scissors form to fit the wire terminals. The central bolt 55 which' holds the arrester elements together makes this construction possible.

In Fig. 9 one arrangement is illustrated for varying the spark gap of the arrester simply by displacing the spark gap teeth in the up er and,j lower discs 26, relative to each ot er. These discs turn on the centre bolt and when the teeth are opposite the spark gap is at a minimum and when the are staggered to the fullest extent the spark gap is at a maximum, thus providing a simple and effective means for adjusting the spark gap by a very fine adjustment.

It is found in practice that this form of arrester has several points of superiority over other spark gap type of arresters heretofore used. The large metallic area surrounding the carborundum wheel seems to relieve the greater part of the electric discharge directly through the carborundum while the surges ofthe current are discharged by comparatively small sparks between the saw teeth across the spark gap and thesel sparks in themselves apparently pass over the surface of the carborundum. Considern able attention has been given in the present invention to making an arrester which could be quickly asmbled and disassembled so that the parts may. be inspected and when necessary, cleaned and reassembled in the same condition as a new arrester and without the possibility of changing the relative operating parts of the device. Moreover the arrester will stand considerable hard usage without breakage or damage to its arts. This arrester can be ada ted without c ange to existing commercia apparatus having various dimensions. y

Having thus described our invention, we

claim:

1.- In a device of the class described, a pair of terminal strips with upwardly turned ends, a reractory whee1,'a cup-shaped metallic plate on each side of said wheel, the

edgies of said plates provided with saw teeth an means through the centre of Vsaid wheel for pivotally clamping said ends and plates' together. v 2. In a device of the class described, a pair .of terminal strips, a refractory block, a pair of similar metallic plates enclosing said block on the sides and partially enclosing it on the edges, said terminal strips placed adjacent saidA plates, a bolt for clamping said parts together, said bolt making electrical contact with said refractory block and insulated from the metallic parts of said device whereby a connection may be made to said block independently of said metallic plates.

3. A lightning arrester of the class described including a carborundum block, a row of spark gap points surrounding the edge of said block, a terminal strip connected With said spark ga points, a bolt through the centre of said b ock clamping said parts together and means including said bolt whereby an electrical connection may be made to said block independently of said terminal strip'.

4. In a lightin arrester the combination of a central re actory block, a pair of similar contact plates arranged one on each side ofsaid block, a terminal strip connected with one of said plates, an insulating bushing for each plate and a clamping bolt passing through said bushings and said block for holding the parts together, said bolt making electrical connection with said block whereby an independent circuit may be connected with said block.

5. A device of the class described including a circular block of refractory material, a cup-shaped dischaving saw toothed edges on each side of said block and enclosing said block and means whereby may be turned on its axis so as to position the teeth of one disc relative to the teeth of the other disc.

6. A device of the class described including a wheel of refractory material, a pair of cup-shaped .discs having saw toothed ed s enclosing said wheel with the saw teee h projecting across the periphery of said wheel, said discs being secured to said wheel by a bolt passing through the contre of said wheel.

Signed at New York in the county of N ewv York and State of New York, this 12th day of July, 1921.

EDWARD A. EVERETT. nmnoN. E. Smm.

one of said discs- 

